RBS and NatWest are no strangers to IT cockups. In December they were hit with a £56m fine from regulators for their IT meltdowns in 2012.

The Bank of England's Prudential Regulation Authority said the IT disaster could have affected the "stability of the financial system it interfered with". ®

Update

A spokeswoman contacted us to say the bank does not yet have an estimate as to when mobile banking will be fully running again. She said: “We are aware that some customers are experiencing difficulty accessing our mobile banking. We’re investigating this and we are working to get it resolved as quickly as possible. In the meantime, our customers can visit one of our branches, use online banking or call us via telephone banking as normal. We apologise to customers for the inconvenience."

Second update

At around 14:30, a spokeswoman told us: "Our Mobile Banking service is currently operating as normal. We apologise to those who experienced difficulties accessing the service today. We will continue to monitor the service."